Cationic layer compounds modified with polymers

ABSTRACT

Halogen-containing synthetic resins can be stabilized with calcium and zinc soaps of which the effectiveness is enhanced by co-stabilizers. 
     The invention relates to special cationic layered hydrotalcite compounds having a specific BET surface of at least 50 m 2  /g which are modified with at least one polymeric additive, to processes for the production of these cationic layer compounds and to their use as co-stabilizers for halogen-containing synthetic resins stabilized with calcium and/or zinc salts.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to special cationic layer compounds having aspecific BET surface of at least 50 m² /g which are modified with atleast one polymeric additive, to processes for the production of thesecationic layer compounds and to their use as co-stabilizers forhalogen-containing synthetic resins stabilized with calcium and/or zincsalts.

2. Discussion of Related Art

It is known that halogen-containing synthetic resins or moldingcompounds produced from them tend to degrade or decompose on exposure toheat or ultraviolet light. To counteract this, heavy metal compoundsbased on lead, tin, barium and/or cadmium are normally used. For reasonsof factory hygiene, however, there is a need to replace these thoroughlyeffective stabilizers by less health-damaging materials. Possiblealternative stabilizers to the heavy metal compounds are, for example,calcium and zinc soaps, but unfortunately they do not perform as well asthe heavy metal compounds so that co-stabilizers have to be used inorder to enhance their stabilizing effect.

German patent DE-C-30 19 632 describes the use of hydrotalcites forinhibiting the thermal or ultraviolet degradation of halogen-containingthermoplastic resins. This patent specification discloses test resultswhich show that, when readily commercially available hydrotalcites areincorporated, for example, in vinyl chloride resins, they accelerate thedechlorination of the resins on heating or even cause decomposition,blackening or foaming of the resins. In addition, it was found thatthese hydrotalcites show poor dispersibility in the resins and adverselyaffect the rheological properties of the resins during molding and alsothe appearance of the molded products obtained. These test results areattributed to the small crystal size of the usual hydrotalcites and tothe large specific BET surface of at least about 50 m² /g and thecoverage of the hydrotalcite particles with water. Accordingly, it isproposed in German patent DE-C-30 19 632 to use hydrotalcites which havea large crystal size and a specific BET surface of no larger than 30 m²/g and which may optionally be coated with an anionic surfactant, suchas sodium stearate. European patent application EP-A-189 899 alsodescribes resin compositions containing hydrotalcites having specificBET surfaces below 30 m² /g. It is known from this European patentapplication that the hydrotalcites can be modified with higher fattyacid esters, anionic surfactants and coupling agents of the silane ortitanium type in order to improve the compatibility of the hydrotalcitewith the resins.

However, cationic layer compounds having such small specific surfacescan only be obtained at considerable expense because the crystallizationof the solid from the aqueous phase has to take place in a pressurereactor at temperatures well above the normal boiling point of water.This involves considerable outlay on equipment and leads to anunsatisfactory volume/time yield on account of the long crystallizationtimes. In addition, the use of hydrotalcites having small specificsurfaces is attended by the disadvantage that hydrogen chloride givenoff during the thermal decomposition of vinyl chloride resins can onlybe trapped over a very small surface.

DESCRIPTION OF THE INVENTION

The problem addressed by the present invention was to provideco-stabilizers for halogen-containing synthetic resins which would becompatible with calcium and zinc compounds, which would be dispersiblein the halogen-containing resins without adversely affecting theirrheological behavior and which would be safe from the point of view offactory hygiene. In addition, the co-stabilizers would be capable oftrapping the products given off during the decomposition ofhalogen-containing synthetic resins, such as hydrogen chloride.

The present invention relates to cationic layer compounds correspondingto general formula I

    [M.sup.(II).sub.x M.sup.(III) (OH).sub.y ](A.sup.n-).sub.z ·mH.sub.2 O                                      (I)

in which

M.sup.(II) represents at least one divalent metal ion,

M.sup.(III) represents at least one trivalent metal ion,

A^(n-) represents an acid anion having a charge n (n=1, 2 or 3),

with the proviso that 1<x<5, 0≦z<y, (y+nz)=2x+3 and 0<m<10,

which have a specific BET surface of at least 50 m² /g and which aremodified with additives, characterized in that they are modified

A) with one or more polymeric additives which are soluble in polarorganic solvents and/or in water having pH values above 8 and which havea molecular weight of 500 to 50,000,

on their own or in combination with one or more additives selected fromthe following groups:

B) polyols containing 3 to 30 carbon atoms and at least two hydroxylgroups,

C) esters of partly and completely epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms,

D) full and partial esters of polyols containing 3 to 30 carbon atomsand 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22carbon atoms and

E) alkyl and aryl phosphites.

The cationic layer compounds corresponding to general formula I arecompounds known per se of which the structure and preparation aredescribed, for example, by W.T. Reichle in Chemtec (January 1986), pages58 to 63. Cationic layer compounds corresponding to general formula I inwhich M.sup.(II) represents at least one divalent metal ion selectedfrom the group consisting of magnesium, calcium, zinc, barium andstrontium, are preferred for the purposes of the invention. In apreferred embodiment, M.sup.(II) represents only one divalent metal ionfrom the group mentioned, more particularly magnesium. In generalformula I, M.sup.(III) best represents at least one trivalent metal ionselected from the group consisting of aluminium, bismuth, antimony,boron, gallium and indium and, preferably, only one trivalent metal ionfrom this group, more preferably aluminium. Cationic layer compoundscorresponding to general formula I, in which A^(n-) represents an acidanion having a charge of n selected from the group of anions consistingof carbonate, hydrogen carbonate, perchlorate, acetate, nitrate,tartrate, oxalate, hydroxide and iodide, preferably carbonate, are mostparticularly preferred. Where reference is made to at least one divalentor at least one trivalent metal ion in the explanation of formula Iabove, it means that different divalent or trivalent metal ions may alsobe present alongside one another in the cationic layer compound. Theindices x, y and z and m may represent whole or broken numbers withinthe limits mentioned above; z may also be zero. Cationic layer compoundscorresponding to general formula I, in which M.sup.(II) representsmagnesium, M.sup.(III) represents aluminium and A^(n-) representscarbonate, are particularly advantageous. One example of this preferredgroup is hydrotalcite which occurs naturally as a mineral and to whichthe composition

    [Mg.sub.6 Al.sub.2 (OH).sub.16 ]CO.sub.3 ·4 H.sub.2 O

is normally assigned (cf. Chimia 24, pages 99-108;1970);

this formula can be converted to general formula I by division by afactor of 2. Particularly suitable are synthetic hydrotalcites which mayalso be called basic aluminium/magnesium carbonates and which may beobtained by the processes described in DE-B-15 92 126 and in DE-A-20 61114 or DE-A 29 05 256. Hydrotalcites corresponding to the formula

    [Mg.sub.4 Al.sub.2 (OH).sub.12 ](CO.sub.3)·mH.sub.2 O

where m is as already defined, which may be produced in accordance withDE-C-33 06 822 are most particularly preferred. According to DE-C-33 06822, hydrotalcites corresponding to the formula [Mg₆ Al₂ (OH)₁₂ ](CO₃)₃·4H₂ O are obtained by reaction of aluminium hydroxide with magnesiumhydroxide or magnesium oxide in the presence of basic magnesiumcarbonate as carbonate ion donor at a temperature of 50° C. to 100° C.and subsequent spray drying of the suspension. According to theinvention, however, the production of the particularly preferredhydrotalcites is not confined to this particular process. Thus, thereaction may also take place in the presence of other carbonate salts,although this is less preferred because of the introduction of foreignions. In addition, the hydrotalcites may also be recovered from thesuspension by other standard separation and drying processes, althoughspray drying is preferred. The ratios in which magnesium, aluminiumand/or carbonate ions are used can also be varied.

Cationic layer compounds produced by any of these processes have aspecific BET surface of at least 50 m² /g and preferably in the rangefrom 70 to 180 m² /g. According to the invention, the expression"specific BET surface" corresponds to the definition given in Rompp'sChemie Lexikon, Vol. 1, 8th Edition, 1979, page 423.

According to the invention, the cationic layer compounds are to bemodified with one or more polymeric additives A) which are soluble inpolar organic solvents and/or water having pH values above 8 andpreferably in the range from 9 to 12 and which have an average (numberaverage) molecular weight of 500 to 50,000. "Soluble" in the context ofthe invention means that more than 0.01% by weight of the polymericadditives are soluble in the solvents and preferably at least 0.1% byweight thereof are soluble in an aqueous solution having a pH value of10 adjusted with alkali metal hydroxides at 20° C.; more particularly,they form completely clear solutions under the described conditions. Inthe context of the invention, polar organic solvents are understood tobe hydrocarbon compounds which are liquid at room temperature (15° to25° C.) and which bear at least one substituent which is moreelectronegative than carbon, including chlorinated hydrocarbons,alcohols, ketones, esters, ethers and/or glycol ethers. Suitable polarorganic solvents are methanol, ethanol, n-butanol, acetone, methyl ethylketone, methyl isobutyl ketone, cyclohexanol, isophorone, ethyl acetate,lactic acid ethyl ester, 2-methoxyethyl acetate, tetrahydrofuran,ethylene glycol monomethyl ether, diethylene glycol monoethyl ether. Thesolubility of the polymeric additives ensures that the surface of thecationic layer compounds can be uniformly modified by one of theprocesses according to the invention to be described in the following.In principle, any of the polymers known to the expert as pigmentdispersants (cf. Kirk-Othmer, "Encyclopedia of Chemical Technology",Vol. 7, 3rd Edition, 1979, pages 840-841 or Ullmann's "Encyclopedia ofIndustrial Chemistry", Vol. A8, 5th Edition, 1987, pages 586-601) may beused as the polymeric additives providing they satisfy the solubilitymolecular and weight requirements. Acrylic acid and methacrylic acidhomo- and copolymers, lignin sulfonates and trimer fatty acids arepreferred polymeric additives. Particularly suitable polymeric additivesare those selected from the group consisting of polymers of acrylic andmethacrylic acid and copolymers thereof with unsaturated monomerscontaining sulfonic acid groups, unsaturated monomers containingphosphonic acid groups, unsaturated aliphatic C₃₋₅ carboxylic acids,amides of unsaturated aliphatic C₃₋₅ carboxylic acids, aminofunctionalunsaturated monomers and/or salts thereof, vinyl acetate, vinylchloride, acrylonitrile, vinylidene chloride, 1,3-butadiene, styrene,alkyl styrenes containing 1 to 4 C atoms in the alkyl group. Examplesinclude polyacrylic acid, polymethacrylic acid (acrylic acid andmethacrylic acid and derivatives thereof are referred to more simplyhereinafter as (meth)acrylic acid or derivatives) and/or salts thereof,such as polysodium (meth)acrylate, copolymers of (meth)acrylic acid withmaleic acid, maleic anhydride, styrene sulfonic acid, o-methyl styrene,2-vinyl pyridine, 1-vinyl imidazole, dimethylaminopropyl(meth)acrylamide, 2-(meth)acrylamido-2-methylpropane sulfonic acid,(meth)acrylamide, N-hydroxydimethyl (meth)acrylamide and/or saltsthereof. Among the polymeric additives, those which are predominantlyanionic in character, i.e. which contain a majority of acid groups infree form or in the form of their salts, are most particularlypreferred. Polymers of (meth)acrylic acid and copolymers thereof withstyrene, alkyl styrenes containing 1 to 4 C atoms in the alkyl group,styrene sulfonic acid, maleic acid and/or salts thereof, particularlysodium salts and maleic anhydride, are especially preferred. Thepolymeric additives best have a molecular weight of 1,000 to 10,000. Thepolymeric additives may be produced by known methods, such as bulk orsolution polymerization (cf. Ullmann's Encyclopadie der technischenChemie, Vol. 19, 4th Edition, pages 2-11, 1980). Processes for thepreparation of lignin sulfonic acid and salts thereof are also describedin Ullmann's Encyclopadie der technischen Chemie, Vol. 16, 4th Edition,pages 254-257, 1978. Trimer fatty acids are commercial products whichare obtained as residue in the distillation of dimer fatty acid, such asPripol®1040 (Unichema) or Emery®1000 (Emery).

According to the invention, the cationic layer compounds may be modifiedwith one or more polymeric additives on their own or in combination withother additives. Polyols containing at least two hydroxyl groups and atotal of 3 to 30 carbon atoms are suitable other additives in group B).Examples of such polyols are diols containing 3 to 30 carbon atoms, suchas butanediols, hexanediols, dodecanediols, and trimethylol propane,pentaerythritol, glycerol and technical oligomer mixtures thereof havingaverage degrees of condensation of 2 to 10. Polyols containing 3 to 30carbon atoms which bear at least one hydroxyl group or an ether oxygenevery three carbon atoms, such as glycerol and/or technicaloligoglycerol mixtures having average degrees of condensation of 2 to10, are most particularly preferred.

The additives of group C) are esters of partly or completely epoxidizedunsaturated carboxylic acids containing 6 to 22 carbon atoms. Suitableesters are esters of monohydric, dihydric and/or trihydric alcoholswhich are completely esterified with epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms, such as methyl, 2-ethylhexyl,ethylene glycol, butanediol, neopentyl glycol, glycerol and/ortrimethylol propane esters of epoxidized lauroleic acid, palmitoleicacid, oleic acid, ricinoleic acid, linoleic acid and/or linolenic acid.Esters of trihydric alcohols and substantially completely epoxidizedunsaturated carboxylic acids containing 12 to 22 carbon atoms arepreferred, esters of glycerol with substantially completely epoxidizedunsaturated carboxylic acids containing 12 to 22 carbon atoms beingparticularly preferred. The carboxylic acid component may be derived,for example, from unsaturated palmitoleic acid, oleic acid, elaidicacid, petroselic acid, ricinoleic acid, linolenic acid, gadoleic acid orerucic acid which are epoxidized by known methods. As usual inoleochemistry, the epoxidized carboxylic acid glycerides may also be thetechnical mixtures obtained by epoxidation of natural unsaturated fatsand unsaturated oils. Epoxidized rapeseed oil, epoxidized unsaturatedsoybean oil and/or epoxidized sunflower oil from new crops is/arepreferably used.

The additives of group D) are full or partial esters obtained by therelevant methods of preparative organic chemistry, for example byacid-catalyzed reaction of polyols with carboxylic acids. Suitablepolyol components are any of those already discussed in connection withgroup B). The acid component is preferably selected from aliphatic,saturated and/or unsaturated carboxylic acids containing 6 to 22 carbonatoms, such as caproic acid, caprylic acid, capric acid, lauric acid,myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleicacid, ricinoleic acid, linoleic acid, linolenic acid, behenic acid orerucic acid. As usual in oleochemistry, the carboxylic acid componentmay also be a technical mixture of the type obtained in the pressurehydrogenation of natural fats and oils. Partial esters of glycerol and,in particular, technical oligoglycerol mixtures having average degreesof condensation of 2 to 10 and saturated and/or unsaturated aliphaticcarboxylic acids containing 6 to 22 carbon atoms are preferred.

Finally, alkyl and aryl phosphites, preferably those corresponding togeneral formula II ##STR1## in which R¹, R² and R³ independently of oneanother represent a C₁₋₁₈ alkyl radical or a phenyl radical, may be usedas the additives of group E). Typical examples of group E) additives aretributyl phosphite, triphenyl phosphite, dimethylphenyl phosphite and/ordimethylstearyl phosphite. Diphenyldecyl phosphite is preferred.

According to the invention, the polymeric additives may be used with oneor more additives from groups B) to E) to modify the cationic layercompounds, the total quantity of additive being in the range from 0.5 to15% by weight, based on cationic layer compounds. Where the polymericadditives are used in combination with other additives, it is preferredto use the polymeric additives in quantities of 10 to 99% by weight and,more particularly, in quantities of 30 to 95% by weight, based on thetotal quantity of additives.

The present invention also relates to processes for the production ofthe cationic layer compounds according to the invention. The first(process 1.) is a process for the production of cationic layer compoundscorresponding to general formula I

    [M.sup.(II).sub.x M.sup.(III) (OH).sub.y ](A.sup.n-).sub.z ·mH.sub.2 O                                      (I)

in which

M.sup.(II) represents at least one divalent metal ion,

M.sup.(III) represents at least one trivalent metal ion,

A^(n-) represents an acid anion having a charge n (n=1, 2 or 3),

with the proviso that 1<x<5, 0≦z<y, (y+nz)=2x+3 and 0<m<10,

which have a specific BET surface of at least 50 m² /g and which aremodified with additives, characterized in that layer compoundscorresponding to formula I are precipitated from aqueous solutions orsuspensions containing the ions M.sup.(II), M.sup.(III) and A^(n-) inthe presence of

A) one or more polymeric additives which are soluble in polar organicsolvents and/or in water having pH values above 8 and which have amolecular weight of 500 to 50,000,

on their own or in combination with one or more additives selected fromthe following groups:

B) polyols containing 3 to 30 carbon atoms and at least two hydroxylgroups,

C) esters of partly and completely epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms,

D) full and partial esters of polyols containing 3 to 30 carbon atomsand 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22carbon atoms and

E) alkyl and aryl phosphites,

dried and optionally redried.

In the first process, the cationic layer compounds according to theinvention are produced in situ. The cationic layer compounds must beformed with a specific BET surface of at least 50 m² /g. This can beachieved with the above-cited conventional processes according toDE-B-15 92 126 or DE-A-20 61 114 or DE-A-29 05 256. At all events, it isimportant to avoid reaction conditions in the production of cationiclayer compounds which, as in European patent application EP-A-189 899,lead to products having specific surfaces of smaller than 30 m² /g. Theprocess is described by way of example in the following with referenceto the particularly preferred hydrotalcite which, according to theinvention, is preferably produced as described in DE-C-33 06 822.According to this document, aluminium hydroxide is reacted withmagnesium hydroxide and/or magnesium oxide in aqueous suspension in thepresence of carbonate ions, with the proviso that the polymericadditives may optionally be present in combination with other additivesfrom groups B) to E). The additives may be added either before ortogether with magnesium hydroxide and/or magnesium oxide to aluminiumhydroxide or before or together with aluminium hydroxide to magnesiumhydroxide and/or magnesium oxide. The additives are best added toaluminium hydroxide with stirring at room temperature (15° to 25° C.)before the reaction with magnesium hydroxide and/or magnesium oxide,preferably magnesium oxide only, takes place. Reaction temperatures of50° to 100° C. are recommended in order to accelerate the subsequentreaction. The quantities of magnesium and aluminium in the form of theirhydroxides or oxides and of carbonate are determined by the desiredhydrotalcite and can be worked out from general formula I. The carbonateions may be introduced in the form of their salts, preferably asmagnesium hydroxide carbonate. The slurry formed during the reaction isthen dried by any of the known methods, preferably by spray drying.Drying is best carried out at temperatures which exceed the boilingpoint of the additives by no more than 10° C. and, more particularly,not at all. In some cases, the additional removal of water by redrying,which is advantageously carried out at temperatures of 110° to 280° C.,for example in a drying cabinet, leads to improved cationic layercompounds according to the invention. This first method gives cationiclayer compounds which are modified very homogeneously with the additivesalready described.

The second process concerns the production of cationic layer compoundscorresponding to general formula I having a specific BET surface of atleast 50 m² /g and modified with additives, characterized in that layercompounds corresponding to formula I are precipitated from aqueoussolutions or suspensions containing the ions M.sup.(II), M.sup.(III) andA^(n-) in the presence of

A) one or more polymeric additives which are soluble in polar organicsolvents and/or in water having pH values above 8 and which have amolecular weight of 500 to 50,000,

dried and optionally redried and the product obtained is ground in thepresence of polar organic solvents or water containing one or moreadditives selected from the following groups:

B) polyols containing 3 to 30 carbon atoms and at least two hydroxylgroups,

C) esters of partly and completely epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms,

D) full and partial esters of polyols containing 3 to 30 carbon atomsand 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22carbon atoms and

E) alkyl and aryl phosphites,

dried and optionally redried.

In the second process (process 2.) for the production of the layercompounds according to the invention, the layer compounds of formula Iare first prepared from aqueous solutions or suspensions only in thepresence of the polymeric additives as in process 1., dried andoptionally redried. Particulars of the production of the cationic layercompounds modified with polymeric additives can be found in thedescription of process 1. The product thus obtained is then thoroughlyground with one or more additives selected from groups B) to E) in thepresence of the polar organic solvents already described or in thepresence of water, preferably in grinding mills and more preferably in aball mill. The ground product is then dried in the usual way, preferablyat temperatures no more than 10° C. above the boiling points of theadditives, and optionally redried as described for process 1.

The third process concerns the production of cationic layer compoundscorresponding to general formula I having a specific BET surface of atleast 50 m² /g and modified with additives, characterized in that layercompounds corresponding to formula I are precipitated from aqueoussolutions or suspensions containing the ions M.sup.(II), M.sup.(III) andA^(n-) in the presence of

B) polyols containing 3 to 30 carbon atoms and at least two hydroxylgroups,

C) esters of partly and completely epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms,

D) full and partial esters of polyols containing 3 to 30 carbon atomsand 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22carbon atoms and

E) alkyl and aryl phosphites,

dried and optionally redried and the product obtained is ground in thepresence of polar organic solvents or water with one or more polymericadditives which are soluble in polar organic solvents and/or in waterhaving pH values above 8 and which have a molecular weight of 500 to50,000, dried and optionally redried.

In the third process (process 3.), layer compounds of formula I arefirst prepared from aqueous solutions or suspensions solely in thepresence of additives from groups B) to E) as in process 1. The productthus obtained is then ground with one or more of the described polymericadditives in the presence of the polar organic solvents alreadydescribed or in the presence of water, dried and optionally redried.Grinding is carried out as in process 2. Drying and redrying have alsobeen described.

The fourth process concerns the production of cationic layer compoundscorresponding to general formula I having a specific BET surface of atleast 50 m² /g and modified with additives, characterized in that layercompounds corresponding to formula I are ground in the presence of polarorganic solvents or water with

A) one or more polymeric additives which are soluble in polar organicsolvents and/or in water having pH values above 8 and which have amolecular weight of 500 to 50,000,

on their own or in combination with one or more additives selected fromthe following groups:

B) polyols containing 3 to 30 carbon atoms and at least two hydroxylgroups,

C) esters of partly and completely epoxidized unsaturated carboxylicacids containing 6 to 22 carbon atoms,

D) full and partial esters of polyols containing 3 to 30 carbon atomsand 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22carbon atoms and

E) alkyl and aryl phosphites,

dried and optionally redried.

In the fourth process (process 4.), cationic layer compounds having aspecific surface of larger than 50 m² /g are thoroughly ground with thepolymeric additives A) on their own or in combination with additivesfrom groups B) to E) in the presence of the polar organic solventsalready described or in the presence of water, preferably in grindingmills and more preferably in a ball mill, subsequently dried in theusual way, preferably in a vacuum drying cabinet and optionally redriedas described. The cationic layer compounds which may be used for process4. are either conventional, already described unmodified cationic layercompounds and/or cationic layer compounds which were modified withadditives from groups B) to E) during the precipitation of the cationiclayer compounds from aqueous solution or suspension in the first step ofprocess 1.

In processes 1. to 4., the polymeric additives A) are added on their ownor in combination with one or more additives from groups B) to E) inquantities of 0.5 to 15% by weight, based on cationic layer compounds.If the polymeric additives are used in combination with other additivesfrom group B), the quantity of polymeric additives A) is preferably 10%by weight to 99% by weight and more preferably 30 to 95% by weight,based on the total quantity of additives. If desired, the cationic layercompounds obtained by process 1. may then be modified with at least oneliquid or low-melting, dispersing additive selected from groups B) to C)by intensive mixing at room temperature (15° to 25° C.) or at atemperature below the decomposition temperatures of the cationic layercompounds and/or the additives, preferably below 300° C. Low-meltingadditives are understood to be additives which can be converted into theliquid state at temperatures below the above-mentioned decompositiontemperatures under normal pressure. If the cationic layer compoundsproduced by process 1. are to be modified in this way, a total of 3 to100% by weight, based on cationic layer compounds, of the additives B)to E) may be present in addition to the quantities mentioned above.

The present invention also relates to the use of cationic layercompounds of the described type as co-stabilizers for halogen-containingsynthetic resins stabilized with calcium and/or zinc salts of carboxylicacids containing 6 to 22 carbon atoms. The cationic layer compoundsaccording to the invention are preferably used as co-stabilizers inhalogen-containing synthetic resins, more particularly in PVC. To thisend, the surface-modified cationic layer compounds are added inquantities of 0.01 to 5 parts by weight and preferably in quantities of0.1 to 3 parts by weight, based on 100 parts by weight resin. Ingeneral, they are mechanically mixed with the resins present in granularform before being subjected to processing, for example by calendering orextrusion. Commercially available zinc and/or calcium salts ofcarboxylic acids containing 6 to 22 carbon atoms are incorporated asconventional stabilizers, generally at the same time as thesurface-modified cationic layer compounds. Other conventional additives,such as the heat stabilizers described in EP-A-189 899, may of coursealso be used. The quantities in which the stabilizers and co-stabilizers(modified cationic layer compound) are used may be varied as required,with the proviso that the total addition of stabilizer makes up from 0.5to 5 parts by weight per 100 parts by weight resin. Accordingly, theminimum quantity of modified cationic layer compounds is at least 0.01%by weight.

The effect of zinc and/or calcium soaps as stabilizers forhalogen-containing synthetic resins is enhanced by the use of thecationic layer compounds according to the invention. In addition, themodified cationic layer compounds as co-stabilizers may readily beincorporated in the halogen-containing synthetic resins withoutadversely affecting their rheological properties.

EXAMPLES

A) Preparation of the modified cationic layer compounds

Example 1

Addition of additive during formation of the cationic layer compound

300 g of an aluminium hydroxide gel having an aluminium content of 0.56mol were stirred with 800 g fully deionized water (FD water) at roomtemperature. The additives or additive mixtures shown in Table 1 werethen added in the quantities indicated and the mixture was heated to 80°C. 61.6 g magnesium hydroxide carbonate, corresponding to 0.64 molmagnesium, and 17.6 g magnesium oxide, corresponding to 0.44 molmagnesium, in powder form were added at the temperature of 80° C. Themixture was then stirred under reflux for 2 hours and, after cooling,was directly spray-dried using a Buchi laboratory spray dryer (air entrytemperature 130° to 160° C., exit temperature 100° to 105° C.). In somecases, the powder-form spray-dried product was redried for 2 hours in alaboratory drying cabinet.

The additives or additive mixtures are listed in Table 1. The quantitiesindicated for the additives represent % by weight, based on thetheoretical yield of cationic layer compound corresponding to theformula [Mg₄ Al₂ (OH)₁₂ ] (CO₃)·4H₂ O. The temperature indicated is theredrying temperature in °C.

A copolymer of 46% by weight styrene, 23% by weight α-methyl styrene and31% by weight acrylic acid having a molecular weight (weight average) of6,000 (copolymer 1) was used as the polymeric additive.

                  TABLE 1                                                         ______________________________________                                        Cationic layer compound modified with                                                                           Redrying                                    Ex.     Additive         Quantity in °C.                               ______________________________________                                        1a      Copolymer 1      2.2      --                                          1b      Copolymer 1      2.2      200                                         1c      Copolymer 1      2.2                                                          and                       200                                                 epoxidized soybean oil                                                                         2.2                                                          (saponification value SV                                                      125, epoxide oxygen                                                           content 5.8% by weight)                                               1d      Copolymer 1      2.2                                                          and                       200                                                 glycerol         2.2                                                  1e      Copolymer 1      2.2                                                          and                       200                                                 epoxidized soybean oil                                                                         2.2                                                          (SV 125; EO 5.8) and                                                          glycerol         2.2                                                  ______________________________________                                    

Example 2

Grinding of the cationic layer compounds with additives

Hydrotalcite of the C 300 type (Giulini Chemie GmbH), specific surface115 m² /g, was used as the cationic layer compound. 19.4 g of thehydrotalcite were ground for 1 hour in a glass ball mill

2a) with copolymer 1 of Example 1 and 80 g fully deionized water,

2b) with copolymer 1 of Example 1 and 80.6 g epoxidized soybean oil (SV125; EO 5.8) and 80 g fully deionized water,

2c) with 1 g of a 60% by weight solution of a copolymer of 95% by weightmethyl acrylate and 5% by weight dimethylaminopropyl methacrylamide (MW5,000) in xylene and 60 g ethyl methyl ketone.

The glass balls were then removed by sieving and the solid was filteredoff. The modified hydrotalcite was then dried at 75° C. in a vacuumdrying cabinet, powdered and redried for 2 hours at 200° C. in a dryingcabinet.

Example 3

Grinding of premodified cationic layer compounds with additives

800 g fully deionized water were added at room temperature to 300 g ofthe aluminium hydroxide gel of Example 1 and, after the addition of 2.5g glycerol, the mixture was heated with stirring to 80° C. 61.6 gmagnesium hydroxide carbonate and 17.6 g magnesium oxide were added tothe mixture as in Example 1. The further procedure was as described inExample 1. A powder-form spray-dried product having a specific BETsurface of 96 m² /g was obtained and was redried for 2 hours at 200° C.in a drying cabinet.

As in Example 2, 19.4 g of this product were ground with 0.6 g copolymer1, 0.6 g epoxidized soybean oil (SV 125; EO 5.8) and 80 g fullydeionized water in a glass ball mill. The glass balls were then removedby sieving as in Example 2 and the solid was filtered and washed withfully deionized water. The hydrotalcite thus modified was then dried at110° C. in a recirculating air drying cabinet, powdered and redried for2 hours at 200° C. in a drying cabinet.

Comparison substances

C1

"Alcamizer® 4" commercial PVC stabilizer of Kyowa Chemical Ind. based onhydrotalcite having a specific BET surface of 8 m² /g (see "Introductionof Alcamizer" Kyowa Chem Ind. Co. Ltd., pages 2-36, Isuriganecho,Higashi-Ku, Osaka).

C2

Spray-dried hydrotalcite prepared in accordance with Example 1 but withno addition of additives and with no redrying.

C3

Spray-dried hydrotalcite prepared in accordance with Example 1, but withno addition of additives. After spray-drying, this hydrotalcite wasredried for 2 hours at 200° C. in a laboratory drying cabinet.

C4

19.4 g hydrotalcite of the C 300 type (Giulini Chemie GmbH), BET surface115 m² /g, were stirred, but not ground, with 0.6 g copolymer 1 and 80 gfully deionized water for two hours at 80° C. The solid was filtered offand the undissolved particles of copolymer 1 were mechanically removed.The solid was then dried at 75° C. in a vacuum drying cabinet, powderedand redried for 2 hours at 200° C.

B) Application Examples

Sheeted-out compounds containing stabilizer mixtures of

0.5 part by weight zinc stearate,

0.5 part by weight calcium stearate,

0.2 part by weight stearoyl benzoyl methane (Rhodiastab® 50)

1.0 part by weight of the substances of Examples 1, 2 and 3 according tothe invention and comparison substances 1 to 4

based on 100 parts by weight suspension polyvinyl chloride having a Kvalue of 65,

were tested for "static stability".

To this end, polyvinyl chloride molding compounds containing stabilizermixtures were processed to test strips on co-rotating laboratory mixingrolls measuring 450×220 mm (Berstorff) at a roll temperature of 170° C.and at a roll speed of 12.5 r.p.m. The approx. 0.5 mm thick strips werecut into square test specimens (edge length 10 mm) which were thenexposed to a temperature of 180° C. in a drying cabinet having 6rotating trays (Heraeus FT 420 R). Samples were taken at 15 minuteintervals and examined for changes in color. Discoloration was evaluatedon a scale of 1 (colorless) to 10 (black, stability failure).

The results are set out in Table 2.

                  TABLE 2                                                         ______________________________________                                        Stability of the PVC molding compounds                                        Additive                                                                      of          Color mark after minutes                                          Example                                                                              Example  0      15  30  45  60  75  90  105  120                       ______________________________________                                        A      1a       1      1   2   3    4   7  10                                 B      1b       1      1   2   3    4   7   9  10                             C      1c       1      1   2   2    4   6  10                                 D      1d       1      2   2   3    4   6   8   9   10                        E      1e       1      2   2   3    5   7   8  10                             F      2a       1.5    2   3   5    8  10                                     G      2b       1      2   2   5    7   9  10                                 H      2c       1      2   3   5    7   9  10                                 I      3        1.5    2   3   4    5   6   7   8   10                        J      C1       1      2   3   5    7  10                                     K      C2       1.5    2   4   8   10                                         L      C3       1      2   4   8   10                                         M      C4       2      3   4   7   10                                         ______________________________________                                    

We claim:
 1. A process for the production of a composition of matter useful as a co-stabilizer for halogen-containing synthetic resins, said process comprising:a) precipitating a cationic layer compound corresponding to general formula:

    [M.sup.(II).sub.x M.sup.(III) (OH).sub.y ](A.sup.n-).sub.z ·mH.sub.2 O                                      (I)

in which M.sup.(II) represents at least one divalent metal ion, M.sup.(III) represents at least one trivalent metal ion, A^(n-) represents an acid anion having a charge n with n=1, 2 or 3, with the proviso that 1<x<5, 0≦z<y, (y+nz)=2x+3 and 0<m<10, said cationic layer compound having a specific BET surface of at least 50 m² /g, from an aqueous solution or suspension containing the ions M.sup.(II), M.sup.(III) and A^(n-) in the presence of one or more polymeric additives which are soluble in polar organic solvents and/or in water having pH values above 8 and which have a molecular weight of 500 to 50,000, andb) drying the compound so precipitated.
 2. A process as claimed in claim 1 wherein said aqueous solution or suspension is further comprised of one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms, and alkyl or aryl phosphites.
 3. A process as claimed in claim 1 wherein, after said drying, the precipitated and dried product is ground in the presence of a solvent or water containing one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms, and alkyl or aryl phosphites.
 4. A process as claimed in claim 1 wherein M.sup.(II) represents a divalent magnesium ion or M.sup.(III) represents a trivalent aluminum ion or A^(n-) represents a carbonate ion.
 5. A process as claimed in claim 1 wherein said layer compound corresponding to general formula 1 is a hydrotalcite.
 6. A process as claimed in claim 1 wherein said polymeric additive is selected from the group consisting of acrylic acid or methacrylic acid homo- or copolymers, lignin sulfonates and trimer fatty acids.
 7. A process as claimed in claim 1 wherein said polymeric additive is selected from the group consisting of polymers of acrylic or methacrylic acid and copolymers thereof with unsaturated monomers containing sulfonic acid groups, unsaturated monomers containing phosphonic acid groups, unsaturated aliphatic C₃₋₅ carboxylic acids, amides of unsaturated aliphatic C₃₋₅ carboxylic acids, aminofunctional unsaturated monomers and/or salts thereof, vinyl acetate, vinyl chloride, acrylonitrile, vinylidene chloride, 1,3-butadiene, styrene or alkyl styrenes containing 1 to 4 C atoms in the alkyl group.
 8. A process as claimed in claim 1 wherein said polymeric additive is selected from the group consisting of polymers of acrylic acid or methacrylic acid and copolymers thereof with styrene, alkyl styrenes containing 1 to 4 C atoms in the alkyl group, styrene sulfonic acid, maleic acid and/or salts thereof or maleic anhydride.
 9. A process as claimed in claim 1 wherein said polymeric additive has a molecular weight of 1,000 to 10,000.
 10. A process as claimed in claim 1 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of C₃₋₃₀ polyols containing at least one hydroxyl group or an ether oxygen atom for every 3 C atoms.
 11. A process as claimed in claim 10 wherein said polyols are selected from the group consisting of glycerol and/or technical oligoglycerol mixtures having average degrees of condensation of 2 to
 10. 12. A process as claimed in claim 1 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of esters of trihydric alcohols and completely epoxidized unsaturated C₁₂₋₂₂ carboxylic acids.
 13. A process as claimed in claim 12 wherein said esters are selected from the group of epoxidized soybean oil, epoxidized rapeseed oil and epoxidized sunflower oil.
 14. A process as claimed in claim 1 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of partial esters of glycerol, technical oligoglycerol mixtures having average degrees of condensation of 2 to 10 and saturated and/or unsaturated aliphatic C₆₋₂₂ carboxylic acids.
 15. A process of claim 1 wherein said polymeric additive comprises from 0.5% to 15% by weight of said cationic layer compound.
 16. A process as claimed in claim 1 wherein said aqueous solution or suspension is further comprised of one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms and alkyl or aryl phosphites,wherein the total quantity of said polymeric additive and said additional additive ranges from 0.5 to 15% by weight of said cationic layer compound, wherein said polymeric additive comprises 10 to 99% by weight, based on the total quantity of additives.
 17. A process as claimed in claim 16 wherein said polymeric additive is 30 to 95% by weight of the total quantity of additives.
 18. A composition of matter produced by the process of claim
 1. 19. A composition of matter as claimed in claim 18 further comprising a calcium and/or zinc salt of a C₆₋₂₂ carboxylic acid.
 20. A method of co-stabilizing a halogen-containing resin comprising mixing a halogen-containing resin with a composition as claimed in claim
 18. 21. A resin composition comprising a halogen-containing synthetic resin and a composition of matter produced by the process of claim
 1. 22. A resin composition as claimed in claim 21 further comprising a calcium and/or zinc salt of a C₆₋₂₂ carboxylic acid.
 23. A process for the production of a composition of matter useful as a co-stabilizer for halogen-containing synthetic resins, said process comprising:a) grinding a cationic layer compound corresponding to general formula:

    [M.sup.(II).sub.x M.sup.(III) (OH).sub.y ](A.sup.n-).sub.z ·mH.sub.2 O                                      (I)

in which M.sup.(II) represents at least one divalent metal ion, M.sup.(III) represents at least one trivalent metal ion, A^(n-) represents an acid anion having a charge n with n=1, 2 or 3, with the proviso that 1<x<5, 0≦z<y, (y+nz)=2x+3 and 0<m<10, said cationic layer compound having a specific BET surface of at least 50 m² /g, in the presence of solvents or water and in the presence of one or more polymeric additives which are soluble in polar organic solvents and/or in water having pH values above 8 and which have a molecular weight of 500 to 50,000, andb) drying the compounds so ground.
 24. A process as claimed in claim 23 wherein said cationic layer compound is, during said grinding, in the presence of one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms and alkyl or aryl phosphites.
 25. A process as claimed in claim 23 wherein, prior to said grinding, said cationic layer compounds are precipitated in the presence of a solvent or water containing one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms and alkyl or aryl phosphites.
 26. A process as claimed in claim 23 wherein M.sup.(II) represents a divalent magnesium ion or M.sup.(III) represents a trivalent aluminum ion or A^(n-) represents a carbonate ion.
 27. A process as claimed in claim 23 wherein said layer compound corresponding to general formula 1 is a hydrotalcite.
 28. A process as claimed in claim 23 wherein said polymeric additive is selected from the group consisting of acrylic acid or methacrylic acid homo- or copolymers, lignin sulfonates and trimer fatty acids.
 29. A process as claimed in claim 23 wherein said polymeric additive is selected from the group consisting of polymers of acrylic or methacrylic acid and copolymers thereof with unsaturated monomers containing sulfonic acid groups, unsaturated monomers containing phosphonic acid groups, unsaturated aliphatic C₃₋₅ carboxylic acids, amides of unsaturated aliphatic C₃₋₅ carboxylic acids, aminofunctional unsaturated monomers and/or salts thereof, vinyl acetate, vinyl chloride, acrylonitrile, vinylidene chloride, 1,3-butadiene, styrene or alkyl styrenes containing 1 to 4 C atoms in the alkyl group.
 30. A process as claimed in claim 23 wherein said polymeric additive is selected from the group consisting of polymers of acrylic acid or methacrylic acid and copolymers thereof with styrene, alkyl styrenes containing 1 to 4 C atoms in the alkyl group, styrene sulfonic acid, maleic acid and/or salts thereof or maleic anhydride.
 31. A process as claimed in claim 23 wherein said polymeric additive has a molecular weight of 1,000 to 10,000.
 32. A process as claimed in claim 23 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of C₃₋₃₀ polyols containing at least one hydroxyl group or an ether oxygen atom for every 3 C atoms.
 33. A process as claimed in claim 32 wherein said polyols are selected from the group consisting of glycerol and/or technical oligoglycerol mixtures having average degrees of condensation of 2 to
 10. 34. A process as claimed in claim 23 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of esters of trihydric alcohols and completely epoxidized unsaturated C₁₂₋₂₂ carboxylic acids.
 35. A process as claimed in claim 34 wherein said esters are selected from the group consisting of epoxidized soybean oil, epoxidized rapeseed oil and epoxidized sunflower oil.
 36. A process as claimed in claim 23 wherein said aqueous solution or suspension is further comprised of one or more additives from the group consisting of partial esters of glycerol, technical oligoglycerol mixtures having average degrees of condensation of 2 to 10 and saturated and/or unsaturated aliphatic C₆₋₂₂ carboxylic acids.
 37. A process of claim 23 wherein said polymeric additive comprises from 0.5% to 15% by weight of said cationic layer compound.
 38. A process as claimed in claim 23 wherein said aqueous solution or suspension is further comprised of the one or more additional additives selected from the following groups:polyols containing 3 to 30 carbon atoms and at least two hydroxyl groups, esters of partly or completely epoxidized unsaturated carboxylic acids containing 6 to 22 carbon atoms, full or partial esters of polyols containing 3 to 30 carbon atoms and 2 to 12 hydroxyl groups with carboxylic acids containing 6 to 22 carbon atoms and alkyl or aryl phosphites,wherein the total quantity of said polymeric additive and said additional additive ranges from 0.5 to 15% by weight of said cationic layer compound, wherein said polymeric additive comprises 10 to 99% by weight, based on the total quantity of additives.
 39. A process as claimed in claim 38 wherein said polymeric additive is 30 to 95% by weight of the total quantity of additives.
 40. A composition of matter produced by the process of claim
 23. 41. A composition of matter as claimed in claim 40 further comprising a calcium and/or zinc salt of a C₆₋₂₂ carboxylic acid.
 42. A method of co-stabilizing a halogen-containing resin comprising mixing a halogen-containing resin with a composition as claimed in claim
 40. 43. A resin composition comprising a halogen-containing synthetic resin and a composition produced by the process of claim
 21. 44. A resin composition as claimed in claim 43 further comprising a calcium and/or zinc salt of a C₆₋₂₂ carboxylic acid.
 45. A process as claimed in claim 1 wherein said BET surface area is from 70 to 180 m² /g.
 46. A composition as claimed in claim 18 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g.
 47. A method as claimed in claim 20 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g.
 48. A resin composition as claimed in claim 21 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g.
 49. A process as claimed in claim 23 wherein said BET surface area is from 70 to 180 m² /g.
 50. A composition as claimed in claim 40 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g.
 51. A method as claimed in claim 42 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g.
 52. A resin composition as claimed in claim 43 wherein the BET surface area of the cationic layer compound in said composition is from 70 to 180 m² /g. 